Originally, Xen stored the 32-bit address of the domain structure in struct
page_info. On x86-64, the physical address was stored, but since all heap
objects were allocated in the 1:1 mapping which started at 0xffff830000000000,
the end result was the same as if we simply chopped off the high bits (actual
implementation in makedumpfile).
Then, during the development of Xen-3.4, this logic was changed several times
for x86-64:
changeset 39517e863cc8 widened the _domain field to 64 bits and stored the
virtual address of struct domain instead of physical address
changeset beba88f6f90d removed the pickle/unpickle macros
changeset 0858f961c77a changed _domain back from unsigned long to u32,
*and* stores the MFN of struct domain instead
All the above changes went into Xen-3.4, and the relation between a domain
address and the contents of the _domain field hasn't changed since then.
That means, when the MADDR space was compressed in Xen-4.0, the type of the
_domain field was changed to _pdx_t, which was specifically invented to
preserve its calculation from the struct domain address.
To sum it up:
1. For all Xen versions before Xen-3.4, the _domain field contains the address
of struct domain (with high bits chopped for x86-64).
2. For all Xen versions starting with Xen-3.4, the _domain field can be
computed from struct domain address as:
(addr - DIRECTMAP_VIRT_START) >> PAGE_SHIFT
Signed-off-by: Petr Tesarik <[email protected]>
---
arch/x86_64.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
--- a/arch/x86_64.c
+++ b/arch/x86_64.c
@@ -402,14 +402,30 @@ int get_xen_basic_info_x86_64(void)
int get_xen_info_x86_64(void)
{
+ crash_xen_info_common_t *xen_crash_info;
int i;
- /*
- * pickled_id == domain addr for x86_64
- */
- for (i = 0; i < info->num_domain; i++) {
- info->domain_list[i].pickled_id =
- info->domain_list[i].domain_addr;
+ xen_crash_info = get_xen_crash_info(NULL);
+ if (xen_crash_info &&
+ (xen_crash_info->xen_major_version >= 4 ||
+ (xen_crash_info->xen_major_version == 3 &&
+ xen_crash_info->xen_minor_version >= 4))) {
+ /*
+ * cf. changeset 0858f961c77a
+ */
+ for (i = 0; i < info->num_domain; i++) {
+ info->domain_list[i].pickled_id =
+ (info->domain_list[i].domain_addr
+ - DIRECTMAP_VIRT_START) >> info->page_shift;
+ }
+ } else {
+ /*
+ * pickled_id == domain addr for x86_64
+ */
+ for (i = 0; i < info->num_domain; i++) {
+ info->domain_list[i].pickled_id =
+ info->domain_list[i].domain_addr;
+ }
}
return TRUE;
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